title: Magnetic separation of malaria-infected red blood cells in various developmental stages.
abstract: Malaria is a serious disease that threatens the public health, especially in developing countries. Various methods have been developed to separate malaria-infected red blood cells (i-RBCs) from blood samples for clinical diagnosis and biological and epidemiological research. In this study, we propose a simple and label-free method for separating not only late-stage but also early-stage i-RBCs on the basis of their paramagnetic characteristics due to the malaria byproduct, hemozoin, by using a magnetic field gradient. A polydimethylsiloxane (PDMS) microfluidic channel was fabricated and integrated with a ferromagnetic wire fixed on a glass slide. To evaluate the performance of the microfluidic device containing the ferromagnetic wire, lateral displacement of NaNO2-treated RBCs, which also have paramagnetic characteristics, was observed at various flow rates. The results showed excellent agreement with theoretically predicted values. The same device was applied to separate i-RBCs. Late-stage i-RBCs (trophozoites and schizonts), which contain optically visible black dots, were separated with a recovery rate of approximately 98.3%. In addition, using an optimal flow rate, early-stage (ring-stage) i-RBCs, which had been difficult to separate because of their low paramagnetic characteristics, were successfully separated with a recovery rate of 73%. The present technique, using permanent magnets and ferromagnetic wire in a microchannel, can effectively separate i-RBCs in various developmental stages so that it could provide a potential tool for studying the invasion mechanism of the malarial parasite, as well as performing antimalarial drug assays.
authors.affiliation: School of Mechanical Engineering, Korea University, Seoul 136-713, Korea.
authors.forename: Jeonghun
authors.initials: J
authors.lastname: Nam
authors.forename: Hui
authors.initials: H
authors.lastname: Huang
authors.forename: Hyunjung
authors.initials: H
authors.lastname: Lim
authors.forename: Chaeseung
authors.initials: C
authors.lastname: Lim
authors.forename: Sehyun
authors.initials: S
authors.lastname: Shin
mesh_terms: D002469:Cell Separation / Q000295:instrumentation / Q000379:methods*; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004867:Equipment Design; D004912:Erythrocytes / Q000166:cytology* / Q000469:parasitology*; D006420:Hemeproteins / Q000032:analysis; D060328:Magnetic Phenomena; D016778:Malaria, Falciparum / Q000469:parasitology*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D010963:Plasmodium falciparum / Q000502:physiology*; D013997:Time Factors
chemical_list: D004129:Dimethylpolysiloxanes; D006420:Hemeproteins; C020753:hemozoin; C013830:baysilon